A blow moulding machine for the production of containers from thermoplastic material has been frequently described in the state of the art already, so that in the following description a discussion of a detailed embodiment of a blow moulding machine is not necessary. For the production of the containers from thermoplastic material a preform is used, which is pre-blown or contoured in a blow mould with positive pressure. The blow mould comprises at least two mould carrier halves pivoted on a common axis. By turning the blowing wheel round an axis the mould carrier halves are closed and the blowing process or the contouring of the containers is started at a certain point within the rotary motion of the blowing wheel. A mould carrier is disclosed for example in the European patent EP 1276 589 B1.
The European patent application EP 0754 537 A1 discloses the possibility of reusing the work fluid in a stretch blow moulding machine. In a stretch blow moulding machine various functional units are operated pneumatically. A high-pressure blowing air tank for extending said preform and an operation air tank for operating said various functional units are provided. The exhaust air circuit of the blow moulds is connected with the operation air tank. Thus part of the used blowing air can be used with the operation air tank for operating the various functional units.
The German patent application 43 402 90 discloses the multiple use of operation air. In an apparatus at least one functional unit is operated pneumatically. The operation is by main operation air supplied to the pneumatic functional element from a main operation air supply. In addition to the main operation air supply at least one supplementary operation air supply is used, which operates at a lower pressure level than the main operation air supply. After an operation of a pneumatic functional element with pressurized air from the operation air supply during a transitional phase a venting into the supplementary operation air supply is done. After the transitional phase the venting of the first pneumatic element is carried out against environmental pressure. A second pneumatical operation is supplied from the supplementary operation air supply.
The German patent application DE 43 402 91 A1 also discloses the multiple use of blowing air. The blowing air is used for shaping a container out of thermoplastic material. After an adjustment of temperature a preform is supplied to a blowing station comprising a blow mould for contouring the container. The preform is placed into the blow mould. The preform is extended with high pressure blowing air. At least one further pneumatic operation is carried out with low pressure air taken from a low pressure air supply. The low pressure air supply has a lower pressure level than the high pressure blowing air supply. After an expansion of the preform high pressure air flowing out of the shaped container held in the blow mould is supplied to the low pressure air supply during a transitional period. The pressure within the low pressure air supply is monitored in order to limit the maximum pressure provided for low pressure air. After a transitional period the container held in the blow mould is vented into the environmental air.
The German patent application DE 10 2004 014 653 A1 discloses a method and an apparatus for manufacturing an in particular heat resistant hollow body. The hollow body is shaped out of a heated preform of thermoplastic material in a contoured blow mould. The shaping is done by directing a first medium into the preform, the medium being stored in a first medium supply under pressure. This is referred to as the pre-blowing phase. The hollow body is final blown by more or less simultaneously stretching the hollow body and directing a second medium into the hollow body from a second medium supply under a higher pressure than the first medium supply. Finally, a third medium, stored in a third medium supply and cooled, is directed into the final blown container. This process is known as the rinsing phase.
The U.S. Pat. No. 7,320,586 B2 discloses an apparatus for the blow moulding of containers. The containers are preferentially bottles made out of a preform, wherein gas is directed into the containers and the gas in the containers is recovered. The apparatus comprises a device for supplying the gas under a first pressure and under a second pressure. A blow mould for shaping the container is also provided. The device also comprises means for the recovery of the gas up to a set pressure level within the container. Furthermore control means are provided which control the recovery unit and the adjustment unit, so that predefined manufacturing conditions are maintained.
The German patent application DE 31 119 25 A1 discloses a method and an apparatus for saving pressurized air, in particular in thermoforming machines. The pressurized air is used for impacting a shaping tool. The pressurized air used in the shaping process, previously released into the atmosphere, is now released in stages. This is done in such a way that the pressurized air still present after the shaping process is partly stored and subsequently supplied to various further loads via suitable valve control and corresponding conduits. By these measures relatively high energy savings are achievable with respect to the entire thermoforming machine.
The German patent DE 10 2004 041 973 B3 discloses air recycling in the blow moulding process. Containers are produced from thermoplastics, wherein a heated preform is pre-blown by supplying low pressure blowing air from a low pressure air supply and subsequently final blown by supplying high pressure blowing air. The high pressure blowing air flowing out of the final blown container is supplied to the low pressure air supply by a switch during a transitional period. Pressure monitoring of the low pressure air supply is provided. After the transitional period the container is vented against an environmental pressure. Control of the pressure of the low pressure air supply provides for a variation of the duration of the transitional period.